<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        body {
            background: #E0E0E0;
        }

        div {
            line-height: 150px;
            text-align: center;
            font-size: 20px;
            font-weight: 900;
        }

        .box {
            height: 150px;
            width: 150px;
            margin: 100px;
        }

        .flat,
        .concave,
        .convex,
        .pressed {
            display: flex;
            justify-content: center;
            align-self: center;
        }

        .flat .left {
            border-radius: 17px;
            background: #e0e0e0;
            box-shadow: 15px 15px 17px #b3b3b3,
                -15px -15px 17px #ffffff;
        }

        .flat .right {
            border-radius: 17px;
            background: #e0e0e0;
            box-shadow: -15px 15px 17px #b3b3b3,
                15px -15px 17px #ffffff;
        }

        .concave .left {
            border-radius: 17px;
            background: linear-gradient(45deg, #cacaca, #f0f0f0);
            box-shadow: 15px -15px 11px #b3b3b3,
                -15px 15px 11px #ffffff;
        }

        .concave .right {
            border-radius: 17px;
            background: linear-gradient(45deg, #cacaca, #f0f0f0);
            box-shadow: 15px -15px 11px #b3b3b3,
                -15px 15px 11px #ffffff;
        }

        .convex .left {
            border-radius: 17px;
            background: linear-gradient(45deg, #f0f0f0, #cacaca);
            box-shadow: 15px -15px 11px #b3b3b3,
                -15px 15px 11px #ffffff;
        }

        .convex .right {
            border-radius: 17px;
            background: linear-gradient(315deg, #f0f0f0, #cacaca);
            box-shadow: -15px -15px 11px #b3b3b3,
                15px 15px 11px #ffffff;
        }

        .pressed .left {
            border-radius: 17px;
            background: #e0e0e0;
            box-shadow: inset 15px 15px 11px #b3b3b3,
                inset -15px -15px 11px #ffffff;
        }

        .pressed .right {
            border-radius: 17px;
            background: #e0e0e0;
            box-shadow: inset -15px -15px 11px #b3b3b3,
                inset 15px 15px 11px #ffffff;
        }
    </style>
</head>

<body>
    <!-- https://neumorphism.io/ -->
    <div class="flat">
        <div class="left box">左平坦</div>
        <div class="right box">右平坦</div>
    </div>
    <div class="concave">
        <div class="left box">左凹槽</div>
        <div class="right box">右凹槽</div>
    </div>
    <div class="convex">
        <div class="left box">左凸槽</div>
        <div class="right box">右凸槽</div>
    </div>
    <div class="pressed">
        <div class="left box">左按下</div>
        <div class="right box">右按下</div>
    </div>
</body>

</html>